The invention relates to a package comprising a housing provided with a recess whose bottom is metallized, and including connectors arranged along the periphery of the recess, and including a connection device inserted in the recess between the integrated circuit and the connectors, this connection device including a substrate that presents an upper surface comprising microstrip lines to connect contact studs of the integrated circuit to the connectors of the housing and a metallized lower surface to form a ground plane.
The invention finds its application in the domain of very high frequency integrated circuits where the frequency of the signals is situated between 30 and 60 GHz.
To date the integrated circuits operating at such high frequencies have come to witness an important development. They can only be marketed when comprising a package arranged for not reducing their performance. Now it applies that, to be more exact, technological progress concerning very high frequency integrated circuits has been faster in the research centers than in the industrial development centers to such an extent that packages capable of accommodating such integrated circuits are not yet found to be marketed having the indispensable performance.
For this purpose, it is good to recall that packages already existing for very high frequency circuits cannot be used in the domain from 1 to 6 GHz, or also packages for digital integrated circuits, neither can then be unreservedly transposed in order to be used in a domain where the frequency is of the order of 10 times higher. For that matter, the technical problems occurring in the 30-60 GHz frequency domain are extremely specific.
Thus, from European Patent Application No. EP 88202608.1 is known a package for digital integrated circuits. This package comprises a housing provided with a recess to accommodate the integrated circuit and contact studs disposed on the housing along the periphery of the recess. This package further comprises a connection device lying in the recess of the housing. This connection device is constituted by a wafer of alumina, itself provided with a central opening to receive the integrated circuit, and carries on its upper surface microstrip lines having an impedance of 50 .OMEGA., in addition to resistors and capacitors arranged radially extending from the edge of the central opening near to the integrated circuit along the periphery near to the recess in the housing. This connection device is also provided with a ground plane disposed on its lower surface to make contact with a ground plane disposed on the bottom of the recess in the package.
In order to connect a ground stud of the integrated circuit to the ground plane of the package, a ground line surrounds the substrate layer through the recess, which causes the distance to be very long for this connection.
This restricts the use of such a system to a frequency domain which is smaller by an order of magnitude than the frequency domain searched for the application of the present invention.
Alternatively, once the integrated circuit and the connection device are in position, each microstrip line having an impedance of 50 .OMEGA. is connected by a short wire to a stud of the housing which wire is extended by a metallic stripline printed on the housing and which line surrounds this housing through the recess to reach its lower surface. This stripline Which constitutes the connection device with the circuits on the outside of the package, is thus a simple conductor and not a connector of a given impedance of 50 .OMEGA.. The package is of the type without pins.
This also restricts the use of such a package for low-frequency integrated circuits or digital circuits, and does not enable to attain the high frequencies searched for the present applications.
Moreover, the housing of this package is of a resin which does not allow of realizing the screening necessary for the operation at the required frequencies. Finally, in the above document, nothing is observed about matters of sealing nor about matters of heat dissipation.
The technical problems posed by the realization of packages for integrated circuits operating at such high levels as 30-60 GHz or over, are the following:
This package is to present at least one line having the given impedance of for example 50 .OMEGA. connecting a very high frequency input or output of the integrated circuit to a connector of the coaxial type having a corresponding impedance, this connection line in fact being a very high frequency (VHF) line over its entire length;
This package is thus to present along its periphery at least one such coaxial connector to establish this connection;
This package is also to present standard connectors located along its periphery and lines for connecting these connectors to d.c. power supply studs of the integrated circuit;
This package is to present a ground plane without discontinuities;
This package is to constitute a screening, be tight, be able to withstand temperatures from -40.degree. to +125.degree. C.;
This package is further to be manufactured in an easy manner and at low cost.
For this purpose it is to be able to accommodate integrated circuits of any dimension without substantial modifications of its structure.